Right now I have a Galaxy S21 on my family's plan with many years of use on the same emails, accounts, profiles, socials etc. A little over a year ago I bought a Pixel 3a secondhand in cash to test GrapheneOS/Anonymous SIM/VoIP. Ultimately I never fully transitioned to that device as I didn't prioritize giving all my contacts new phone number, new email, new socials (if I wanted to be on certain socials at all at that point).
But now my upgrade is available on my family's plan and I have the opportunity to get a newer Pixel, but I am not ready to use GrapheneOS on it from the get-go. Would that compromise the privacy-centered approach of using GrapheneOS on the same phone if I used the Pixel normally with all my old accounts on stock OS prior? Or would it be no different than getting a "clean" Pixel that I would only use GrapheneOS from the start with.